As the next-generation radio communication system for performing a higher speed communication as compared with the 3rd-generation and 3.5th-generation radio communication systems operated at present, LTE (Long Term Evolution) has been standardized in 3GPP (3rd Generation Partnership Project) which is the standardization body of a radio communication system.
The technical specifications of the LTE have been specified as 3GPP Release 8, and Release 9 which is an upgrade version of Release 8, and LTE Advanced which is a sophisticated version of the LTE, have been currently considered. In LTE Advanced, the adoption of relay transmission using a radio relay station called a relay node is planned (for example, see Non-Patent Document 1).
The radio relay station is a low-output relay base station connected to the radio base station (macro base station) via radio. The radio terminal connected to the radio relay station performs communication with the radio base station via the radio relay station. By installing a radio relay station in a cell end and a coverage hole of a radio base station such that a radio terminal communicates indirectly with the radio base station via the radio relay station, communication can be performed under better conditions as compared to when the radio terminal communicates directly with the radio base station.